1. Field of the Invention
This invention relates generally to power regulation and, more particularly, to monitoring and controlling the operation of electrical devices.
2. Description of the Related Art
Energy monitoring and control systems are widely used to provide centralized monitoring and control of the loads in electrical systems. In buildings, the loads typically include a number of devices and sub-systems, the most prominent of which from an energy consumption standpoint include the heating, cooling, and lighting systems. Energy monitoring and control systems are rapidly becoming a desired element of the electrical system in small facilities, such as homes, and in large facilities, such as factories, hotels, offices, schools, hospitals, and public buildings. One reason is because there is an ongoing emphasis on energy conservation and a demand for increased effectiveness and reduced cycle time in finding and correcting load problems. There is also an emphasis on decreasing utility costs by using electrical devices less and by eliminating inefficient devices and replacing them with more efficient ones.
However, as of yet there is not a satisfactory way of accurate knowing the electrical power used by various household appliances so that inefficient uses of energy can be eliminated. Since budget planning depends on the amount of energy used during different periods such as the time of day, day of week, or season of the year, it is advantageous to know how much energy is used during various time periods and which particular devices use the most energy. While it is possible to obtain a monthly, daily, or weekly total for aggregate home energy use by reading the outside utility meter, such a practice is awkward and cumbersome. Furthermore, the only information that can be obtained from most utility meters is the total energy used. It generally cannot be determined which particular devices contribute the most to the total amount of energy used within any given time frame.
Another emphasis has been on controlling the operation of electrical devices to better control the amount of energy they use. In the past, systems have been available for automatically controlling certain household appliances from a central location. These systems typically use a power line modem, which is a transmitter/receiver capable of operating over conventional AC 120/240 volt wiring. Examples of these types of systems are shown in U.S. Pat. No. 4,174,517 to Mandell and U.S. Pat. No. 4,418,333 to Schwarzbach. In both of these systems, a control unit can be programmed to initiate certain functions within various appliances depending upon the time of day. For example, lights can be programmed to automatically turn on at dark and a coffee maker can be programmed to automatically turn on at a given hour in the morning. However, neither Schwarzbach nor Mandell provides any way for monitoring energy usage of the various appliances or devices connected to either system. Accordingly, there is a need for a better power monitoring and control system.